Disk drive systems have undergone significant evolution in a relatively short time. Current designs often have a plurality of disks maintained in a common stack, along with a head stack assembly that may include a unitary, rigid actuator arm body (e.g., “E” block) having a plurality of rigid, non-deflectable, vertically spaced actuator arms or tips on which a plurality of flexible suspensions or load beams are fixedly mounted (e.g., via staking). Heads are mounted on the individual load beams and read/write information from the plurality of disks, with two load beams extending into the space between adjacent disks.
Each disk includes a plurality of tracks which are concentrically disposed about an axis about which the plurality of disks rotate. Information may be stored in each of these tracks. Access to other tracks, and thereby other data storage areas on a disk, is provided by moving (e.g., pivoting) the actuator body via a voice coil motor or the like to simultaneously move all load beams and their corresponding heads to a different radial position relative to their corresponding disk. There is at least one known disk drive design which is admitted to be prior art which mounts a plurality of individual actuator arms on a bearing hub, and which clamps these individual actuator arms together and maintains the same in a certain fixed positional relation by a threaded interconnection. Specifically, an external portion of the bearing hub is threaded and a nut is engaged therewith to clamp the actuator arms “down” onto the bearing hub.
Both of the above-noted designs suffer from a number of disadvantages in at least some respect. Solid actuator bodies with load beams separately attached thereto can be relatively costly to fabricate, assemble, test, and rework. Threaded interconnections increase the potential for the generation of particulates within the disk drive encasement which can adversely affect one or more aspects of its operation. Therefore, it would be desirable to have a more cost effective approach for assembling a head stack assembly which avoided particulate generation, particularly for the “low end” disk drive market.
Retainer rings have been used to mount a head/arm assembly on a pivot bearing. In this regard, the head/arm assembly is mounted on the pivot bearing so as to be located between a flange of the pivot bearing and a retainer ring slot that is formed on an outer wall of the pivot bearing. A frustumly-shaped arbor is disposed against the end of the pivot bearing to allow a retainer ring to be mounted on the outer wall of the pivot bearing. Advancing the retainer ring relative to the arbor expands the same to a sufficient diameter so as to be able to be disposed on the outer wall of the pivot bearing. Once on the outer wall of the pivot bearing, the retainer ring is advanced along a constant diameter portion of the pivot bearing until it “snaps” into the retainer ring slot. This approach provides at least certain advantages in the assembly of a head stack assembly. However, it still requires additional tooling.